Sarah Michelle Gellar made her name as Buffy the Vampire Slayer more than a decade ago, and tonight, she’s back in the TV spotlight starring in the premiere of The Crazy Ones alongside Robin Williams.

“That is the bucket list, to work with an Academy Award-winning actor and one of the greatest standup comics of all time,” Gellar says of costarring with Williams.

And the feeling is mutual. In his Parade cover story, Williams said, “I’m having such a blast doing [the show] with Sarah. She’s a sweet woman.” On the CBS comedy, Williams and Gellar play a father-daughter duo running an ad agency.

Gellar’s new starring role coincides with another project that’s important to her: spreading the word about pertussis, or whooping cough. The mom of two (daughter Charlotte, 3, and son Rocky, 1) with husband Freddie Prinze Jr. is leading a campaign to encourage adults to get vaccinated to avoid spreading the re-emerging disease to young children, who are particularly vulnerable.

“Having children is the greatest gift anyone’s ever given me, and if I can help protect anyone else’s gift, then it’s not just my pleasure, but it’s my responsibility to do it,” Gellar says.

The actress, 36, talked to Parade.com about the premiere of The Crazy Ones, what it’s like on set (“It’s a big party!”), and how her own family has helped prepare her for the role.

On pre-premiere jitters.“I’m so nervous and so excited. It’s a weird combination. I think it’s like getting married. You can’t wait for the day and you’re so excited, but you’re also really, really nervous about the day. We’ve worked really hard. The episodes get better and better and I’m really proud of it, and I’m excited to finally get to share it with everybody. I hope they laugh.”

On whether she’ll be following reactions to the premiere.“In our profession, you have to be so careful. You can be torn apart so easily, just as much as you can be brought up, you can be torn down. I advise anyone in my position to be very careful with what you read and what you watch and what you listen to. For me, I don’t make a show for the critics, I make it for the fans, and I just hope they like it.”

On what it’s like on The Crazy Ones set.“It’s a big party! I’ve been doing this job for 32 years, and I’ve never had this much fun. I mean, literally, I am the luckiest. I keep pinching myself. I am so grateful for everything in my life, because this is the most fun I’ve ever had at work.”

(Courtesy CBS)

On meeting and working with Robin Williams.“I was so nervous meeting him. I mean, he’s a legend! The first time I met him, he leaned over at the table read and said to me, ‘I’m so nervous.’ And I was like, ‘What? Yeah, I’m pretty nervous too.’ But to my kids, he’s Uncle Robin. To me, he’s the kindest, most generous comedian, actor, and person. He calls me every night on the way home: How did I feel about the work? Did I get home in time to see the kids? How are the kids? What do they want for their birthdays? If I went on and gloated about him the way I want to, you would totally think I was making him up.”

On who she wants to guest star on The Crazy Ones (Kelly Clarkson appears in the premiere).“[Show creator] David E. Kelley and I have this joke. The show is about an ad agency, so I want Flo, from the insurance commercials. I want my character to direct Flo in a commercial. But yesterday, I did get Josh Groban to sing to me on camera, which was great.”

On portraying a father-daughter relationship with Williams.“For me, it’s really interesting, because I didn’t have a father growing up, so when I play the character, it was all what I learned from my friends or what I witnessed. But now, I have children, and I watch my relationship that my husband has with the children, and especially the father-daughter relationship, because it is a very specific relationship. So I’m learning, but I would say Robin Williams makes me a better parent, and being a parent makes me a better actor opposite Robin Williams, because either way it can be very hard to keep a straight face.”

On how she does manage to keep a straight face.“I do the best I can, and after every episode we have outtakes, and all of America can witness how hard it is to keep a straight face. Honestly, as good as the episodes are, the part we all wait for as a crew is to see what they outtakes use. A lot of them they can’t put on network television. Maybe they’ll do a red band DVD one day of the outrageous outtakes.”

On what she has in common with her character.“For my character, it’s about finding her inner crazy one. Robin’s character is crazy, and he’s afraid he’s losing the sanity to the crazy, and my character is trying to find her inner crazy. That’s something that I had to learn, because I’ve been working since I was a young child, and I took things so seriously. Then you have children, and you have to learn to let go a little bit and find the inner crazy.”

On balancing career and family.“It’s the hardest thing I’ve ever done, working and having children and wanting to be as present as you can for the children, and as present as you can for your job. It’s very, very difficult. There’s no such thing as a supermom. We just do the best we can. That’s why I’m here today, because if there’s one extra thing I can do to save one child, ten children, or a thousand children from pertussis, then that’s what I’m going to do.”

On the importance of getting vaccinated against pertussis.“Every person can say, ‘Oh, I wanted to go visit my friend’s newborn, but I had a cold so I didn’t go.’ Well, why would you also potentially expose them to something they can’t fight? And the best way to stop the spread of pertussis is with the Tdap booster. [Whooping cough] is an epidemic at this point, which is an incredibly scary word, and there’s so much going on in your world as a new parent. You’re so overwhelmed with information and I just thought this is a great way that I could help.”